Only few encapsulation techniques have been described in the art as a manner for protecting and delivering cosmetic/pharmaceutical actives or for protecting the bioactivity of biologics, i.e. stabilization such as enzymes and cells.
One technique in the art is to entrap hydrophilic cosmetic, chemical, biological or pharmaceutical active material compositions in liposomes or vesicular structures. Their structure integrities are known to be sensitive to the presence of surfactants. Another entrapment technique is to encapsulate hydrophilic cosmetic, chemical, biological or pharmaceutical active material compositions in water in oil in water (W/O/W) multiple emulsions. For example, EP 0120967 B1 describes a process of making W/O/W oil and fat composition for food. The oil phase is not an alkoxysilane composition. EP 0174377 B2 describes a method of making W/O/W complex emulsion for medicinal and cosmetic use.
WO-A-98/31333 describes sunscreen-doped sol-gel materials and a method for their preparation comprising condensation polymerization of a metal or semi-metal alkoxide or ester in the presence of at least one sunscreen ingredient, resulting in the entrapment of the sunscreen ingredients within the formed sol-gel matrix.
U.S. Pat. No. 6,303,149 describes a process for preparing sol-gel microcapsules loaded with functional molecules by emulsifying sol-gel precursors and the functional molecules in an aqueous solution, and mixing the emulsion with an acidic, neutral or basic aqueous solution to obtain a suspension of microcapsules.
EP-A-281034 describes a perfume encapsulated and/or clathrated in a matrix of an organic polymer prepared from a metal alkoxide such as tetraethyl orthosilicate (TEOS). An aqueous dispersion or solution of perfume and TEOS is treated with an acid catalyst to cause hydrolysis, then with a base catalyst to cause polymerization to a gel.
EP-A-934773 describes microcapsules whose capsule wall comprises organopolysiloxane synthesized by condensing a compound of the formula RnSi(OH)mY(4-m-n) where m=1-4; n=0-3; R represents an organic group with a C atom directly bonded to a Si atom; and Y is an alkoxy group, H or a siloxy group.
WO-A-01/80823 describes a therapeutic or cosmetic composition comprising microcapsules of diameter 0.1-100 μM having a core-shell structure. The core includes at least one active. The shell comprises an inorganic polymer obtained by a sol-gel process, and releases the active after topical application.
WO-A-03/066209 describes a process of making lipophilic cosmetic, chemical, or pharmaceutical active material compositions encapsulated within a shell obtained from the emulsion polymerization products of tetraalkoxysilane. The process of making these microcapsules is a one kettle process without removal of the continuous phase.
WO-A-03/066209 describes an encapsulation process by ex-situ emulsion polymerization from tetraalkoxysilanes and the surfactant concentration in the starting cationic emulsion.
FR 2876028A1 describes the encapsulation of plant extracts in precipitated silica. This process is not suitable for the encapsulation of hydrophilic cosmetic, chemical, biological or pharmaceutical active material compositions.
JP 2004331617 A2 and JP 2003238342 A2 describe W/O emulsion compositions containing silylated peptide-silane compound copolymers for cosmetics.
The bioactivity of biologics is very sensitive to the conditions in which they are used. Many attempts to improve their robustness have been made. One consists of immobilization of the biologics by covalent bonding onto surfaces. However the immobilization can lead to significant biologic loss and only delays the loss of bioactivity.
A recent approach consists of the encapsulation of biologics into a sol-gel matrix coated onto a surface. Some drawbacks to the use of this approach is that the shrinking of the matrix during the sol-gel process can affect the enzymatic molecular conformation and therefore its activity. In addition, a coating limits the surface for exchange between the encapsulated biologic and the substrate present in the reaction vessel.
Many of these aforementioned processes are not suitable for the encapsulation of hydrophilic materials because of the conditions or techniques used. In addition, the capsules formed by the aforementioned processes do not provide capsules suitable for long-term entrapment of hydrophobic materials or improving the stability of hydrophilic materials such as biologics. Thus, there is a need for a process for encapsulating hydrophilic materials such as cosmetics, chemicals, biologics or pharmaceutical active material compositions wherein the encapsulated materials have improved stability or the ability to entrap the hydrophobic material.